path: root/cloudinit/config/cc_mounts.py

# Copyright (C) 2009-2010 Canonical Ltd.
# Copyright (C) 2012 Hewlett-Packard Development Company, L.P.
#
# Author: Scott Moser <scott.moser@canonical.com>
# Author: Juerg Haefliger <juerg.haefliger@hp.com>
#
# This file is part of cloud-init. See LICENSE file for license information.

"""Mounts: Configure mount points and swap files"""

import logging
import math
import os
import re
from logging import Logger
from string import whitespace
from textwrap import dedent

from cloudinit import subp, type_utils, util
from cloudinit.cloud import Cloud
from cloudinit.config import Config
from cloudinit.config.schema import MetaSchema, get_meta_doc
from cloudinit.settings import PER_INSTANCE

MODULE_DESCRIPTION = """\
This module can add or remove mountpoints from ``/etc/fstab`` as well as
configure swap. The ``mounts`` config key takes a list of fstab entries to add.
Each entry is specified as a list of ``[ fs_spec, fs_file, fs_vfstype,
fs_mntops, fs-freq, fs_passno ]``. For more information on these options,
consult the manual for ``/etc/fstab``. When specifying the ``fs_spec``, if the
device name starts with one of ``xvd``, ``sd``, ``hd``, or ``vd``, the leading
``/dev`` may be omitted.

Any mounts that do not appear to either an attached block device or network
resource will be skipped with a log like "Ignoring nonexistent mount ...".

Cloud-init will attempt to add the following mount directives if available and
unconfigured in `/etc/fstab`::

    mounts:
        - ["ephemeral0", "/mnt", "auto",\
"defaults,nofail,x-systemd.requires=cloud-init.service", "0", "2"]
        - ["swap", "none", "swap", "sw", "0", "0"]

In order to remove a previously listed mount, an entry can be added to
the `mounts` list containing ``fs_spec`` for the device to be removed but no
mountpoint (i.e. ``[ swap ]`` or ``[ swap, null ]``).

The ``mount_default_fields`` config key allows default options to be specified
for the values in a ``mounts`` entry that are not specified, aside from the
``fs_spec`` and the ``fs_file``. If specified, this must be a list containing 6
values. It defaults to::

    mount_default_fields: [none, none, "auto",\
"defaults,nofail,x-systemd.requires=cloud-init.service", "0", "2"]

Non-systemd init systems will vary in ``mount_default_fields``.

Swap files can be configured by setting the path to the swap file to create
with ``filename``, the size of the swap file with ``size`` maximum size of
the swap file if using an ``size: auto`` with ``maxsize``. By default no
swap file is created.
"""

example = dedent(
    """\
    # Mount ephemeral0 with "noexec" flag, /dev/sdc with mount_default_fields,
    # and /dev/xvdh with custom fs_passno "0" to avoid fsck on the mount.
    # Also provide an automatically sized swap with a max size of 10485760
    # bytes.
    mounts:
        - [ /dev/ephemeral0, /mnt, auto, "defaults,noexec" ]
        - [ sdc, /opt/data ]
        - [ xvdh, /opt/data, auto, "defaults,nofail", "0", "0" ]
    mount_default_fields: [None, None, auto, "defaults,nofail", "0", "2"]
    swap:
        filename: /my/swapfile
        size: auto
        maxsize: 10485760
    """
)

distros = ["all"]

meta: MetaSchema = {
    "id": "cc_mounts",
    "name": "Mounts",
    "title": "Configure mount points and swap files",
    "description": MODULE_DESCRIPTION,
    "distros": distros,
    "examples": [
        example,
        dedent(
            """\
        # Create a 2 GB swap file at /swapfile using human-readable values
        swap:
            filename: /swapfile
            size: 2G
            maxsize: 2G
        """
        ),
    ],
    "frequency": PER_INSTANCE,
    "activate_by_schema_keys": [],
}

__doc__ = get_meta_doc(meta)

# Shortname matches 'sda', 'sda1', 'xvda', 'hda', 'sdb', xvdb, vda, vdd1, sr0
DEVICE_NAME_FILTER = r"^([x]{0,1}[shv]d[a-z][0-9]*|sr[0-9]+)$"
DEVICE_NAME_RE = re.compile(DEVICE_NAME_FILTER)
# Name matches 'server:/path'
NETWORK_NAME_FILTER = r"^.+:.*"
NETWORK_NAME_RE = re.compile(NETWORK_NAME_FILTER)
WS = re.compile("[%s]+" % (whitespace))
FSTAB_PATH = "/etc/fstab"
MNT_COMMENT = "comment=cloudconfig"
MB = 2**20
GB = 2**30

LOG = logging.getLogger(__name__)


def is_meta_device_name(name):
    # return true if this is a metadata service name
    if name in ["ami", "root", "swap"]:
        return True
    # names 'ephemeral0' or 'ephemeral1'
    # 'ebs[0-9]' appears when '--block-device-mapping sdf=snap-d4d90bbc'
    for enumname in ("ephemeral", "ebs"):
        if name.startswith(enumname) and name.find(":") == -1:
            return True
    return False


def is_network_device(name):
    # return true if this is a network device
    if NETWORK_NAME_RE.match(name):
        return True
    return False


def _get_nth_partition_for_device(device_path, partition_number):
    potential_suffixes = [
        str(partition_number),
        "p%s" % (partition_number,),
        "-part%s" % (partition_number,),
    ]
    for suffix in potential_suffixes:
        potential_partition_device = "%s%s" % (device_path, suffix)
        if os.path.exists(potential_partition_device):
            return potential_partition_device
    return None


def _is_block_device(device_path, partition_path=None):
    device_name = os.path.realpath(device_path).split("/")[-1]
    sys_path = os.path.join("/sys/block/", device_name)
    if partition_path is not None:
        sys_path = os.path.join(
            sys_path, os.path.realpath(partition_path).split("/")[-1]
        )
    return os.path.exists(sys_path)


def sanitize_devname(startname, transformer, log, aliases=None):
    log.debug("Attempting to determine the real name of %s", startname)

    # workaround, allow user to specify 'ephemeral'
    # rather than more ec2 correct 'ephemeral0'
    devname = startname
    if devname == "ephemeral":
        devname = "ephemeral0"
        log.debug("Adjusted mount option from ephemeral to ephemeral0")

    if is_network_device(startname):
        return startname

    device_path, partition_number = util.expand_dotted_devname(devname)
    orig = device_path

    if aliases:
        device_path = aliases.get(device_path, device_path)
        if orig != device_path:
            log.debug("Mapped device alias %s to %s", orig, device_path)

    if is_meta_device_name(device_path):
        device_path = transformer(device_path)
        if not device_path:
            return None
        if not device_path.startswith("/"):
            device_path = "/dev/%s" % (device_path,)
        log.debug("Mapped metadata name %s to %s", orig, device_path)
    else:
        if DEVICE_NAME_RE.match(startname):
            device_path = "/dev/%s" % (device_path,)

    partition_path = None
    if partition_number is None:
        partition_path = _get_nth_partition_for_device(device_path, 1)
    else:
        partition_path = _get_nth_partition_for_device(
            device_path, partition_number
        )
        if partition_path is None:
            return None

    if _is_block_device(device_path, partition_path):
        if partition_path is not None:
            return partition_path
        return device_path
    return None


def suggested_swapsize(memsize=None, maxsize=None, fsys=None):
    # make a suggestion on the size of swap for this system.
    if memsize is None:
        memsize = util.read_meminfo()["total"]

    sugg_max = memsize * 2

    info = {"avail": "na", "max_in": maxsize, "mem": memsize}

    if fsys is None and maxsize is None:
        # set max to default if no filesystem given
        maxsize = sugg_max
    elif fsys:
        statvfs = os.statvfs(fsys)
        avail = statvfs.f_frsize * statvfs.f_bfree
        info["avail"] = avail

        if maxsize is None:
            # set to 25% of filesystem space
            maxsize = min(int(avail / 4), sugg_max)
        elif maxsize > ((avail * 0.9)):
            # set to 90% of available disk space
            maxsize = int(avail * 0.9)
    elif maxsize is None:
        maxsize = sugg_max

    info["max"] = maxsize

    if memsize < 4 * GB:
        minsize = memsize
    elif memsize < 16 * GB:
        minsize = 4 * GB
    else:
        minsize = round(math.sqrt(memsize / GB)) * GB

    size = min(minsize, maxsize)

    info["size"] = size

    pinfo = {}
    for k, v in info.items():
        if isinstance(v, int):
            pinfo[k] = "%s MB" % (v / MB)
        else:
            pinfo[k] = v

    LOG.debug(
        "suggest %s swap for %s memory with '%s' disk given max=%s [max=%s]'",
        pinfo["size"],
        pinfo["mem"],
        pinfo["avail"],
        pinfo["max_in"],
        pinfo["max"],
    )
    return size


def create_swapfile(fname: str, size: str) -> None:
    """Size is in MiB."""

    errmsg = "Failed to create swapfile '%s' of size %sMB via %s: %s"

    def create_swap(fname, size, method):
        LOG.debug(
            "Creating swapfile in '%s' on fstype '%s' using '%s'",
            fname,
            fstype,
            method,
        )

        if method == "fallocate":
            cmd = ["fallocate", "-l", "%sM" % size, fname]
        elif method == "dd":
            cmd = [
                "dd",
                "if=/dev/zero",
                "of=%s" % fname,
                "bs=1M",
                "count=%s" % size,
            ]

        try:
            subp.subp(cmd, capture=True)
        except subp.ProcessExecutionError as e:
            LOG.info(errmsg, fname, size, method, e)
            util.del_file(fname)
            raise

    swap_dir = os.path.dirname(fname)
    util.ensure_dir(swap_dir)

    fstype = util.get_mount_info(swap_dir)[1]

    if (
        fstype == "xfs" and util.kernel_version() < (4, 18)
    ) or fstype == "btrfs":
        create_swap(fname, size, "dd")
    else:
        try:
            create_swap(fname, size, "fallocate")
        except subp.ProcessExecutionError:
            LOG.info("fallocate swap creation failed, will attempt with dd")
            create_swap(fname, size, "dd")

    if os.path.exists(fname):
        util.chmod(fname, 0o600)
    try:
        subp.subp(["mkswap", fname])
    except subp.ProcessExecutionError:
        util.del_file(fname)
        raise


def setup_swapfile(fname, size=None, maxsize=None):
    """
    fname: full path string of filename to setup
    size: the size to create. set to "auto" for recommended
    maxsize: the maximum size
    """
    swap_dir = os.path.dirname(fname)
    if str(size).lower() == "auto":
        try:
            memsize = util.read_meminfo()["total"]
        except IOError:
            LOG.debug("Not creating swap: failed to read meminfo")
            return

        util.ensure_dir(swap_dir)
        size = suggested_swapsize(
            fsys=swap_dir, maxsize=maxsize, memsize=memsize
        )

    mibsize = str(int(size / (2**20)))
    if not size:
        LOG.debug("Not creating swap: suggested size was 0")
        return

    util.log_time(
        LOG.debug,
        msg="Setting up swap file",
        func=create_swapfile,
        args=[fname, mibsize],
    )

    return fname


def handle_swapcfg(swapcfg):
    """handle the swap config, calling setup_swap if necessary.
    return None or (filename, size)
    """
    if not isinstance(swapcfg, dict):
        LOG.warning("input for swap config was not a dict.")
        return None

    fname = swapcfg.get("filename", "/swap.img")
    size = swapcfg.get("size", 0)
    maxsize = swapcfg.get("maxsize", None)

    if not (size and fname):
        LOG.debug("no need to setup swap")
        return

    if os.path.exists(fname):
        if not os.path.exists("/proc/swaps"):
            LOG.debug(
                "swap file %s exists, but no /proc/swaps exists, being safe",
                fname,
            )
            return fname
        try:
            for line in util.load_file("/proc/swaps").splitlines():
                if line.startswith(fname + " "):
                    LOG.debug("swap file %s already in use", fname)
                    return fname
            LOG.debug("swap file %s exists, but not in /proc/swaps", fname)
        except Exception:
            LOG.warning(
                "swap file %s exists. Error reading /proc/swaps", fname
            )
            return fname

    try:
        if isinstance(size, str) and size != "auto":
            size = util.human2bytes(size)
        if isinstance(maxsize, str):
            maxsize = util.human2bytes(maxsize)
        return setup_swapfile(fname=fname, size=size, maxsize=maxsize)

    except Exception as e:
        LOG.warning("failed to setup swap: %s", e)

    return None


def handle(
    name: str, cfg: Config, cloud: Cloud, log: Logger, args: list
) -> None:
    # fs_spec, fs_file, fs_vfstype, fs_mntops, fs-freq, fs_passno
    def_mnt_opts = "defaults,nobootwait"
    uses_systemd = cloud.distro.uses_systemd()
    if uses_systemd:
        def_mnt_opts = (
            "defaults,nofail,x-systemd.requires=cloud-init.service,_netdev"
        )

    defvals = [None, None, "auto", def_mnt_opts, "0", "2"]
    defvals = cfg.get("mount_default_fields", defvals)

    # these are our default set of mounts
    defmnts: list = [
        ["ephemeral0", "/mnt", "auto", defvals[3], "0", "2"],
        ["swap", "none", "swap", "sw", "0", "0"],
    ]

    cfgmnt = []
    if "mounts" in cfg:
        cfgmnt = cfg["mounts"]

    LOG.debug("mounts configuration is %s", cfgmnt)

    fstab_lines = []
    fstab_devs = {}
    fstab_removed = []

    if os.path.exists(FSTAB_PATH):
        for line in util.load_file(FSTAB_PATH).splitlines():
            if MNT_COMMENT in line:
                fstab_removed.append(line)
                continue

            try:
                toks = WS.split(line)
            except Exception:
                pass
            fstab_devs[toks[0]] = line
            fstab_lines.append(line)

    device_aliases = cfg.get("device_aliases", {})

    for i in range(len(cfgmnt)):
        # skip something that wasn't a list
        if not isinstance(cfgmnt[i], list):
            log.warning(
                "Mount option %s not a list, got a %s instead",
                (i + 1),
                type_utils.obj_name(cfgmnt[i]),
            )
            continue

        start = str(cfgmnt[i][0])
        sanitized = sanitize_devname(
            start, cloud.device_name_to_device, log, aliases=device_aliases
        )
        if sanitized != start:
            log.debug("changed %s => %s" % (start, sanitized))

        if sanitized is None:
            log.debug("Ignoring nonexistent named mount %s", start)
            continue
        elif sanitized in fstab_devs:
            log.info(
                "Device %s already defined in fstab: %s",
                sanitized,
                fstab_devs[sanitized],
            )
            continue

        cfgmnt[i][0] = sanitized

        # in case the user did not quote a field (likely fs-freq, fs_passno)
        # but do not convert None to 'None' (LP: #898365)
        for j in range(len(cfgmnt[i])):
            if cfgmnt[i][j] is None:
                continue
            else:
                cfgmnt[i][j] = str(cfgmnt[i][j])

    for i in range(len(cfgmnt)):
        # fill in values with defaults from defvals above
        for j in range(len(defvals)):
            if len(cfgmnt[i]) <= j:
                cfgmnt[i].append(defvals[j])
            elif cfgmnt[i][j] is None:
                cfgmnt[i][j] = defvals[j]

        # if the second entry in the list is 'None' this
        # clears all previous entries of that same 'fs_spec'
        # (fs_spec is the first field in /etc/fstab, ie, that device)
        if cfgmnt[i][1] is None:
            for j in range(i):
                if cfgmnt[j][0] == cfgmnt[i][0]:
                    cfgmnt[j][1] = None

    # for each of the "default" mounts, add them only if no other
    # entry has the same device name
    for defmnt in defmnts:
        start = defmnt[0]
        sanitized = sanitize_devname(
            start, cloud.device_name_to_device, log, aliases=device_aliases
        )
        if sanitized != start:
            log.debug("changed default device %s => %s" % (start, sanitized))

        if sanitized is None:
            log.debug("Ignoring nonexistent default named mount %s", start)
            continue
        elif sanitized in fstab_devs:
            log.debug(
                "Device %s already defined in fstab: %s",
                sanitized,
                fstab_devs[sanitized],
            )
            continue

        defmnt[0] = sanitized

        cfgmnt_has = False
        for cfgm in cfgmnt:
            if cfgm[0] == defmnt[0]:
                cfgmnt_has = True
                break

        if cfgmnt_has:
            log.debug("Not including %s, already previously included", start)
            continue
        cfgmnt.append(defmnt)

    # now, each entry in the cfgmnt list has all fstab values
    # if the second field is None (not the string, the value) we skip it
    actlist = []
    for x in cfgmnt:
        if x[1] is None:
            log.debug("Skipping nonexistent device named %s", x[0])
        else:
            actlist.append(x)

    swapret = handle_swapcfg(cfg.get("swap", {}))
    if swapret:
        actlist.append([swapret, "none", "swap", "sw", "0", "0"])

    if len(actlist) == 0:
        log.debug("No modifications to fstab needed")
        return

    cc_lines = []
    needswap = False
    need_mount_all = False
    dirs = []
    for line in actlist:
        # write 'comment' in the fs_mntops, entry,  claiming this
        line[3] = "%s,%s" % (line[3], MNT_COMMENT)
        if line[2] == "swap":
            needswap = True
        if line[1].startswith("/"):
            dirs.append(line[1])
        cc_lines.append("\t".join(line))

    mount_points = [
        v["mountpoint"] for k, v in util.mounts().items() if "mountpoint" in v
    ]
    for d in dirs:
        try:
            util.ensure_dir(d)
        except Exception:
            util.logexc(log, "Failed to make '%s' config-mount", d)
        # dirs is list of directories on which a volume should be mounted.
        # If any of them does not already show up in the list of current
        # mount points, we will definitely need to do mount -a.
        if not need_mount_all and d not in mount_points:
            need_mount_all = True

    sadds = [WS.sub(" ", n) for n in cc_lines]
    sdrops = [WS.sub(" ", n) for n in fstab_removed]

    sops = ["- " + drop for drop in sdrops if drop not in sadds] + [
        "+ " + add for add in sadds if add not in sdrops
    ]

    fstab_lines.extend(cc_lines)
    contents = "%s\n" % "\n".join(fstab_lines)
    util.write_file(FSTAB_PATH, contents)

    activate_cmds = []
    if needswap:
        activate_cmds.append(["swapon", "-a"])

    if len(sops) == 0:
        log.debug("No changes to /etc/fstab made.")
    else:
        log.debug("Changes to fstab: %s", sops)
        need_mount_all = True

    if need_mount_all:
        activate_cmds.append(["mount", "-a"])
        if uses_systemd:
            activate_cmds.append(["systemctl", "daemon-reload"])

    fmt = "Activating swap and mounts with: %s"
    for cmd in activate_cmds:
        fmt = "Activate mounts: %s:" + " ".join(cmd)
        try:
            subp.subp(cmd)
            log.debug(fmt, "PASS")
        except subp.ProcessExecutionError:
            log.warning(fmt, "FAIL")
            util.logexc(log, fmt, "FAIL")


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